Project Summary/Abstract: Oxidative stress caused from exposure to environmental toxins results in DNA damage that is repaired by the DNA repair machinery. 8-oxoguanine (8-oxoG) is the most commonly formed DNA lesion, which is recognized and removed by 8-oxoguanine glycosylase (OGG1). The function of OGG1 is important to prevent propagation of DNA error and to mediate transcription of genes responsible for the response to oxidative stress. The inability of cells to perform these tasks can lead to autoimmune and neurodegenerative diseases, cancer, and aging. In addition to DNA oxidation, cysteines can also be targeted for oxidative modification under oxidative stress. OGG1 contains 8 cysteine residues which are potentially targeted for modification in the presence of environmental toxins. This proposal seeks to elucidate the role of cysteine in OGG1 in DNA repair and transcription in response to oxidative stress. Biochemical characterization of OGG1 cysteine mutants is proposed in specific aim 1 to look at the function of cysteine in DNA binding, enzymatic activity, conformational changes, and in protein-protein interactions. These studies will be initiated during the K99 mentored phase and then continued independently during the R00 phase. The second aim will focus on in vivo cell culture work to understand the role of cysteine in DNA repair and in gene regulation and also to identify OGG1 modifications resulting from environmental toxin treatment. The proposed work in this aim will be initiated during the mentored phase, and the technical expertise gained during the mentored phase will be employed during my independent work to accomplish the proposed goals. This work will clarify the role of OGG1 modification in disease initiation and progression and will help in predicting the biological effect of toxin exposure. This work will also provide a foundation for targeted drug design. The long-term goal for this award is to transition into an independent academic research program to explore the comprehensive molecular mechanism of the DNA damage response under oxidative stress and how modifications in the DNA repair machinery lead to disease. To achieve the goals of this award, I assembled a team of mentors with expertise in environmental science, proteomics, redox biochemistry, DNA glycosylases, DNA repair, and gene transcription. This team will also provide me with mentoring in career development for transitioning into independence and establishing and running a successful lab. Further training will be acquired from attending special topic workshops and courses on grant writing and career development offered both at and outside of Yale University. Additional opportunities to attend and present at conferences and to mentor students and postdocs along with continued preparation of manuscripts will be complementary for my long-term goal of establishing an independent research program. These tools will be essential to gain technical training and for career development to establish a successful research program to study the molecular mechanism of the DNA damage response under oxidative stress and its role in disease.